Follicle-Stimulating Hormone (FSH) is a crucial hormone involved in regulating reproductive processes, including the growth of ovarian follicles in females and sperm production in males. The **FSH test** measures the level of FSH in the blood to assess reproductive health and hormone function. It is typically performed by drawing a blood sample, which is then analyzed in a laboratory. The test is commonly used to evaluate fertility issues, menstrual irregularities, menopause, and conditions like polycystic ovary syndrome (PCOS) in women, and to assess testicular function or low sperm count in men. It is often administered at specific times in a woman’s menstrual cycle (such as the early follicular phase) to assess ovarian reserve or pituitary function, or when infertility or reproductive issues are suspected in either sex. The FSH test can also be used to diagnose conditions affecting the pituitary or gonads.